I started work on Tarsnap in late 2006, and over the course of 3 years
I have written about 38 thousand lines of code. (The missing year is
split between time I spent doing cryptographic research which
redefined the field of
key derivation functions and time I've spent writing a key-value
store which I hope to release soon.) This is an average of roughly
one thousand lines of code per month, which is pretty much the limit
to how quickly I can write high quality "never need to look at this
again because it will never break" code.

In addition to the code I wrote, the Tarsnap client software uses 33
thousand lines of code from libarchive; this would have taken
me at least 3 years to produce, and — seeing as archive-processing
code is full of messy format-parsing and special cases — it's
exactly the sort of code I'm not good at writing.

The Tarsnap server code, on the other hand, relies on Amazon
S3 for durable back-end storage (as I wrote in an earlier blog post,
Tarsnap synthesizes a
log-structured file system on top of S3); my estimate is that this
would take me 25–50 thousand lines of code and at least two years
to replicate, and — seeing as testing distributed systems is very
difficult without distributed hardware — a non-trivial capital
expenditure, too. (I'm sure that S3 as a whole is much larger than the
size I quote, but Tarsnap only needs a relatively small proportion of
the features S3 provides.)

Jeff Bezos often speaks of Amazon Web Services as supplying
"undifferentiated heavy lifting" — or "muck" — to startups,
since everybody needs storage, compute power, and bandwidth, yet those
are very rarely what differentiates one startup from the next; open
source software, in contrast, is often extremely differentiated, but is
no less useful to the particular startups which can benefit from it.
Web Services and Open Source Software, while being almost polar
opposites, still have one vital element in common: They can allow one
founder to do what would otherwise require several. If I stepped out of
a time machine into the year 2000, it would take three Colin Percivals
to launch Tarsnap, not just one.

Tarsnap is not a single-founder startup. Tarsnap is a single
equity founder startup. To coin a phrase, I have two
zero-equity co-founders:
Amazon Web Services, and
libarchive:
They each save me just as much work as a co-founder would, and they
don't even ask for a share of the company. Who are your zero-equity
co-founders?